Method of repairing cracks in metal walls



c. MICHAELS METHOD OF REPAIRING CRACKS IN METAL WALLS Filed July 1, 1942INVENTOR. CHARLES M/CHAELS Patented Oct. 31, 1944 'KUNIFTFED TLSTATES.PATENT OF REPAIRING CRACKSIN METAL WALLS Charles Michaels, Flushing, N.Application July 1; 1942, Serial No. 449.242-

ioiaims. '(Cl. 29.148)

'This invention relates to repaired casting cracks and methods of making'such repairs. It is particularly directed to a method for repairingheatcracl'rs' in cylinderblo'c'ks or he'a'ds 'for interrial combustionengines; and the like cra'cksin metalstr'uctures.

" Anobject of the present invention is to provide a: method "ofthecharac'ter described, consisting in stitching along the crack andwelding the screws used in the stitching operation to each other and tothecasting.

Yet aiurther object of thisinvention is to provide an improved processof the character described, in which the s'cre'wsu'sed in' the stitchingoperation are set at an angle to the surface of the cracked wall beingrepaired, so as to increase the number ofthreads on the screws embeddedwithin the'wall, therebypermitting repairof even relatively thin crackedWalls.

A still further object of this invention is toprov'ide in a process ofthe character'de'scribed; consisting musing weld metal which hassubstantially'thesamecoeflicient of expansion as the metal otwhich thecracked casting is made; and which weld'metal'nevertheless has a highermelting point'than' theme'tal of' the casting Whereby said weld metalserves asheat insulation "for the screws used in stitching the crack;and to prevent the screws from loosening.

' Another'object of this invention is to'providea highly improvedprocessof the characten'described, which shall be'economical to: carry out,

and which shall yet be practical and'efiicient to a high degree.

'Other' objects of this invention will in part b'e obvious and in parthereinafterpointed out.

The invention accordingly consists in the combination of steps, featuresofconstructiomcombinations. of elements, and arrangement ofi partswhich. will be exemplified in'the method and the scope of applicationwill be indicated inthe following claims. 7 l .In the accompanyingdrawing, in which is shown one of the various possible illustrative' 40construction hereinafter'described," and of vwhich the crack is drilled,

Fig. 5'is a View similar toFig. 4, and illustrating a still furtherstep;

Fig. 6 is a view similar to Fig. 5. all the screws inserted and peened;

Fig. .7 is a view similar to Fig. 6 and showing the upper ends "of thepeened' screws ground ofi and the uppere'nds of the screws again'peened; Fig. 8 is a view similar to Fig. 7, but showing the grooveformed in the top'of the casting along the line in the crack;

' Fig. 9 is 'a cross-sectionalwiew taken on line 99j'0'f Fig. 8;

' -Fig."10 is a top plan view'of the structure shown in Fig.9;

"Fig. 11- is a cross-sectional view similar to Fig. 8; after the weldingoperation; 1

Fig; 12 is a cross-sectional view taken on line l 2-.l2"of Fig. 11; andl Fig. 13 is a view-similar to Fig; 12, but after the excess weldedmetal is-ground down. 'Referringljnow. in detail :to the drawing, Illdesignatesapartof a casting. such as an engine casing, and II designatesaccrack, such as a heat crack, which is often caused in engines, such asinternalcombustion for automobiles and trucks. -Inaccordancewith-thepresent invention, the cracked casting Ill is first'stitchedalong the crack. To carry-out;this-.operation, there is firstdrilled an-opening- |2= at-one end of the crack. The drilled openingispreferably at an angle as shown in Fig. 3. Anangle of about 30 degreesto and showing the vertical has beenfoundpractical. The drilled openingl2 preferably does not go entirely through thewall of the. casing,although it may be drilled completely therethrough if desired.

The drilled hole i2 is thentapped as illustrated in Fig. 4. A screw I5is thenscrewed into the. tapped opening l3. Said screws may bema-de ofmalleable ,iron,.-soft steel or carbon, steel, although soft steel oriron screws have been found most desirable.

i .The screw is preferably considerably longer thanthetapped opening sothat a portion of the screw projects above the uppersurface of thecasting wall Ill. =The,upper,end of the screw [5 is .then, cut off at apointabout two threads above theupper, surface, of .the castingwall.,The next opening 12 is then drilled parallel to the last screw l5 butpartially overlapping the same,

,so. that a portion ofthe last screw is also drilled.

The overlap is preferablyegual tosubstantially thethickness of thethrea'dqf the screw 1 5. The operation is repeated until the entire.length of tapped and has screws inserted therein.

The upper ends of the screws l5 are then peened as shown at I8, in Fig.6 of the drawing,

chiselled or milled out to form a groove 20 running along the crack.Groove 20 may be of dovetailed cross-section, as illustrated in Fig. 9of the drawing, or of square cross-section, or any other suitablecross-section. The groove may be about of an inch below the uppersurface of the casting wall. The groove is preferably wider than thediameter of the screws, as is likewiseillustrated Fig. 9 of the-drawing.The screws are centered relative to the-groove.

The upper ends of the screws are then welded together preferably by-arcwelding. Nickel alloy electrodes are preferable, although'steel orbronze welding alloysmay be used. The welding metal should have acoefiicient of: expansion almost the same as that of cast iron, but yethave a higher melting point than cast iron, so thatthe welding metalfilling the groove 20 will serve as an insulation for the screws l5. Forthis purpose, nickel alloy electrodes containing mostly nickel andsmaller amounts of copper andiron have been found practical.

The'weldin'g metal will project above the upper surface of the casting:wall, :as illustrated at 22, in Fig. 12 of the drawing. The surplus orexcess metal may then be grounded downto form a smooth sur'face23; levelwith-the surface of the casting, as shown in Fig. 13of the drawing.

If the casting wall is heavy, the slot or groove 20 may be cutbeforedrilling-or inserting the screws-and insuch case,- the' screws arechiselled or otherwise cut 'down to below the upper'surrace of thecasting wall. Furthermore if the crack is away rrem the combustionchamber or any i'na"chined surfaces, the slot may be omitted andtheexpos'ed ends of the screwswel'ded. If the 'slot "is omitted aroughsurface results, and therefore the slot can billy be omitted where arough surface does not matter.

Y I---have fou'nd cracks repaired as described above, will 'not onlyseal the crack against'water leakage from the water jacket, but willalso seal against combustion pressures which may exceed 500 poundspersquare inch. Furthermore, the

-'weld metal aids in insulating'the heat generated in the combustionchambers of internal com bbustion engine cylinders which heat may exceedIt will thus be seen that there is provided a device and method in whichthe several objects of this invention are achieved, and which is welladapted to meet theconditions of practical use.

As various possible embodiments might. be

made of the above invention, and as various changes might be made inthejembodiment above set forth, it isto bejunderstood that all matterherein set forth or shown in the accompanying drawing is to beinterpreted as illustrative an not 'in' alim'iting sense.

Havi'figth'us "assented invention; .1 cl as new and desire to"secufebyLttr's" Pat" 1. A method "for repairing" 'a crack in awall,consisting in stitching alongthe crack with cohtacting screws, thencutting a groove in the upper surface of the wall along the crack widerthan the screws, and then hot welding the stitched screws along thecrack to fill the groove with welded metal.

2. A method of repairing a crack in' a metal wall, consisting indrilling a hole at one end of the crack, at an inclination to the outersurface of said'wall, tapping the drilled hole, inserting a screw in thetapped hole,- drillinganother hole parallel to the screw and overlappingthe screw, tapping the last hole and inserting a screw therein, andrepeating the operation substantially along the entire length of thecrack, cutting off upper portions of the screws, and peening the exposedends of the screws, cutting a groove along the crack and cutting downthe upper ends of the screws to about the level of the bottom of thegroove, and then hot welding the upper end of the screws within thegroove, filling the groove with welded metal.

3. A method of repairing a crack in a metal wall, consisting in drillinga hole at one end of the crack, at an inclination to the outer surfaceof said wall, tapping the drilled hole, inserting a screw in the tappedhole, drilling another hole parallel to the screw and overlapping thescrew. tapping the last hole and inserting a screw therein, andrepeating the operation substantially along the entire length ofthecrack, cutting of!" upper portions of the screws, and peening theexposed ends of the screws, cutting a groove alongthe crack and cuttingdown the upper 4 ends of the screws to about the level of the above thegroove.

4. A method of repairing a crack in a casting. consisting in stitchingalong the crack with contacting, parallel screws disposed at an inclinedangle to the exposed surface of the cracked cast ing, each screw havinga groove receiving part of an adjacent screw, and with the screwsextending through the major thickness of the cast-- ing wall, but notentirely through said wall. and using soft iron screws in the stitchingoperation. and forming a groove along the crack, and hot welding theends of the screws within the groove.

5. A methodof repairing a crack in a metal wall, consisting in drillinga hole at one end of the crack at an inclination to the wall, tappingthe drilled hole, inserting the screw into the tapped hole, drillinganother hole parallel to the screw in overlapped relation to the screw,tapping the last hole, inserting a screw therein. repeating theoperation substantially along the entire length of the crack, cuttingoff upper portions of thescrews to leave about two threads of the screwsexposed above the surface of the wall, peening the exposed ends of thescrews, then cutting off upper portions of the screws to a height ofabout half a thread above the surface of said wall, and again peeningthe ends of said screws. 4

6. A method of repairing a crack in a metal wall, consisting in drillinga hole at one end' tire length of the craclg cutting off upper portionsof the screws toileave about two threads of the screws exposed above thesurface of the wall, peening the exposed; ends of the screws, thencutting oil upper portions of the screws to a height of abouthalf athread above the surface of said wall, and again peening the ends ofsaid screws, said holes being drilled substantially through said wall,but not entirely through said wall.

7. A method of repairing a crack in a metal wall, consisting indrilling'a hole at one end of the crack at an inclination to the wall,tapping the drilled hole, inserting the screw into repeating theoperation substantially along the entire length of the crack, cuttingoff upper portions of the screws to leave about two threads of thescrews exposed above the surface of the wall, peening the exposed endsof the screws, then cutting off upper portions of the screws to a heightof about half a thread above the surface of said wall, and again peeningthe ends of said screws, said holes being drilled substantially throughsaid wall, but not entirely through said wall, cutting a groove in thesurface of said wall along the crack, together with the upper ends ofthe screws, and welding the upper ends of the screws by arc welding tofill the groove the tappedhole, drilling another hole parallel 15 withwelded metal.

to the screw in overlappedrelation to the screw, tapping the last hole,inserting a screw therein,

CHARLES MICHAELS.

